Pyrimidine prodrugs for the treatment of viral infections and further diseases

ABSTRACT

This invention relates to pyrimidine prodrug derivatives, processes for their preparation, pharmaceutical compositions, and their use in therapy.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 16/338,256, filed on Mar. 29, 2019, which is a 35 U.S.C. § 371 filing of International Application No. PCT/EP2017/074600, filed Sep. 28, 2017, which application claims priority to European Application No. 16191568.1, filed Sep. 29, 2016. The entire contents of these applications are incorporated herein by reference in their entirety.

The present invention relates to pyrimidine prodrug derivatives and the use of said pyrimidine prodrug derivatives in the treatment of viral infections, immune disorders, and cancer, or as a vaccine adjuvant, whereby the induction of a T helper 1 (Th1) immune response is desired.

For instance, in the treatment of chronic hepatitis B (HBV), a Th1 response to reinvigorate exhausted virus-specific CD8⁺ T cells in the infected organs would be highly beneficial (Science 1999, 284, 825-829; J. Virol. 2003, 77, 68-76). Such a response is induced by the innate immune system, in particular by stimulating Toll-like receptors (TLR) such as TLR3, 4, 7, 8 and 9 (Clin. Transl. Immunol. 2016, 5(5):e85). TLR8 agonists induce one of the strongest Th1 response in human cells, via the secretion of IL-12p70 and the upregulation of CD40 or OX40L activation markers and indirectly IFN□ (J Immunol. 2006, 176(12):7438-46; Hum Immunol. 2011 January; 72(1):24-31; J Leukoc Biol. 2012, 91(1):105-17), which have shown their potential ex vivo to treat chronic HBV (PLoS Pathog. 2013, 9, e1003208; J. Exp. Med. 2014, 211, 2047-2059; PLoS Path. 2013, 9, e1003490; PLoS Pathog. 2014, 10, e1004210).

Only one TLR8 agonist, administered by subcutaneous injection, is currently in development for cancer indications (Clin. Cancer Res. 2014, 20, 3683; Cancer Immunol. Immunother. 2013, 62, 1347; WO2012/045089. See also US20080234251, US20100029585). Therefore, there exists a strong need for orally-available TLR8 agonists to treat infections such as chronic HBV.

In accordance with the present invention a compound of formula (I) is provided

or a pharmaceutically acceptable salt, solvate or polymorph thereof, wherein R_(1A) is selected from hydrogen, a substituted or unsubstituted C₁₋₃ alkyl, heterocycle, or a substituted or unsubstituted phosphoramidate, R_(1B) is selected from hydrogen, a substituted or unsubstituted C₁₋₃ alkyl, heterocycle, or a substituted or unsubstituted phosphoramidate, with the exception that R_(1A) and R_(1B) are not both hydrogen, R₂ is a C₁₋₈ alkyl, which is optionally substituted by a hydroxyl group.

The present invention concerns a prodrug composition of a pharmaceutical compound. The pharmaceutical compound is characterized by bioavailability of 50% or less and a molecular weight in the range of 100-1000 Daltons. Also described is a method of delivering a pharmaceutical compound to an individual including the step of orally administering said prodrug to an individual. The prodrug moiety is attached to the pharmaceutical compound wherein the modification allows the TLR8 agonist potential to be attenuated. The prodrug is enzymatically cleaved prior to or at the site of the liver to yield the pharmaceutical compound, such that the pharmaceutical compound is delivered to the individual limiting TLR8 agonism prior to the liver.

In a first embodiment the present invention provides compounds of formula (I) wherein R_(1A) and/or R_(1B) are a substituted or unsubstituted phosphoramidate and wherein R₂ is a C₁₋₆ alkyl preferably substituted by a hydroxyl group.

In a second embodiment the present invention provides compounds of formula (I) wherein R_(1A) and/or R_(1B) are methyl and wherein R₂ is a C₆-alkyl substituted by a hydroxyl group.

The compounds of formula (I) in any stereochemical form and their pharmaceutically acceptable salt, solvate or polymorph thereof have activity as pharmaceuticals, in particular as inducers of interferon.

So, in a further aspect the present invention provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof together with one or more pharmaceutically acceptable excipients, diluents or carriers.

Furthermore a compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof according to the current invention, or a pharmaceutical composition comprising said compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof can be used as a medicament.

Another aspect of the invention is that a compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof, or said pharmaceutical composition comprising said compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof can be used accordingly in the treatment of a disorder in which the induction of interferon is involved.

The term “alkyl” refers to a straight-chain or branched-chain saturated aliphatic hydrocarbon containing the specified number of carbon atoms.

“Heterocycle” refers to molecules that are saturated or partially saturated and include tetrahydrofuran, tetrahydropyran, dioxane or other cyclic ethers. Heterocycles containing nitrogen include, for example azetidine, morpholine, piperidine, piperazine, pyrrolidine, and the like. Other heterocycles include, for example, thiomorpholine, dioxolinyl, and cyclic sulfones.

Pharmaceutically acceptable salts of the compounds of formula (I) include the acid addition and base salts thereof. Suitable acid addition salts are formed from acids which form non-toxic salts. Suitable base salts are formed from bases which form non-toxic salts.

The compounds of the invention may also exist in unsolvated and solvated forms. The term “solvate” is used herein to describe a molecular complex comprising the compound of the invention and one or more pharmaceutically acceptable solvent molecules, for example, ethanol.

The term “polymorph” refers to the ability of the compound of the invention to exist in more than one form or crystal structure.

The compounds of the present invention may be administered as crystalline or amorphous products. They may be obtained for example as solid plugs, powders, or films by methods such as precipitation, crystallization, freeze drying, spray drying, or evaporative drying. They may be administered alone or in combination with one or more other compounds of the invention or in combination with one or more other drugs. Generally, they will be administered as a formulation in association with one or more pharmaceutically acceptable excipients. The term “excipient” is used herein to describe any ingredient other than the compound(s) of the invention. The choice of excipient depends largely on factors such as the particular mode of administration, the effect of the excipient on solubility and stability, and the nature of the dosage form.

The compounds of the present invention or any subgroup thereof may be formulated into various pharmaceutical forms for administration purposes. As appropriate compositions there may be cited all compositions usually employed for systemically administering drugs. To prepare the pharmaceutical compositions of this invention, an effective amount of the particular compound, optionally in addition salt form, as the active ingredient is combined in intimate admixture with a pharmaceutically acceptable carrier, which carrier may take a wide variety of forms depending on the form of preparation desired for administration. These pharmaceutical compositions are desirably in unitary dosage form suitable, for example, for oral, rectal, or percutaneous administration. For example, in preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed such as, for example, water, glycols, oils, alcohols and the like in the case of oral liquid preparations such as suspensions, syrups, elixirs, emulsions, and solutions; or solid carriers such as starches, sugars, kaolin, diluents, lubricants, binders, disintegrating agents and the like in the case of powders, pills, capsules, and tablets. Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit forms, in which case solid pharmaceutical carriers are obviously employed. Also included are solid form preparations that can be converted, shortly before use, to liquid forms. In the compositions suitable for percutaneous administration, the carrier optionally comprises a penetration enhancing agent and/or a suitable wetting agent, optionally combined with suitable additives of any nature in minor proportions, which additives do not introduce a significant deleterious effect on the skin. Said additives may facilitate the administration to the skin and/or may be helpful for preparing the desired compositions. These compositions may be administered in various ways, e.g., as a transdermal patch, as a spot-on, as an ointment. The compounds of the present invention may also be administered via inhalation or insufflation by means of methods and formulations employed in the art for administration via this way. Thus, in general the compounds of the present invention may be administered to the lungs in the form of a solution, a suspension or a dry powder.

It is especially advantageous to formulate the aforementioned pharmaceutical compositions in unit dosage form for ease of administration and uniformity of dosage. Unit dosage form as used herein refers to physically discrete units suitable as unitary dosages, each unit containing a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Examples of such unit dosage forms are tablets (including scored or coated tablets), capsules, pills, powder packets, wafers, suppositories, injectable solutions or suspensions and the like, and segregated multiples thereof.

Those of skill in the treatment of infectious diseases will be able to determine the effective amount from the test results presented hereinafter. In general it is contemplated that an effective daily amount would be from 0.01 mg/kg to 50 mg/kg body weight, more preferably from 0.1 mg/kg to 10 mg/kg body weight. It may be appropriate to administer the required dose as two, three, four or more sub-doses at appropriate intervals throughout the day. Said sub-doses may be formulated as unit dosage forms, for example, containing 1 to 1000 mg, and in particular 5 to 200 mg of active ingredient per unit dosage form.

The exact dosage and frequency of administration depends on the particular compound of formula (I) used, the particular condition being treated, the severity of the condition being treated, the age, weight and general physical condition of the particular patient as well as other medication the individual may be taking, as is well known to those skilled in the art. Furthermore, it is evident that the effective amount may be lowered or increased depending on the response of the treated subject and/or depending on the evaluation of the physician prescribing the compounds of the instant invention. The effective amount ranges mentioned above are therefore only guidelines and are not intended to limit the scope or use of the invention to any extent.

EXPERIMENTAL SECTION Preparation of 2 and 3

In a closed vessel, diethyl chlorophosphate (0.3 mL, 2.08 mmol) was added dropwise to a suspension of 1 (For synthesis of 1 see WO2012/136834)(0.5 g, 2.08 mmol) in CHCl₃ (20 mL) at room temperature for 5 min, and then Et₃N (0.38 mL, 2.71 mmol) was added dropwise. The reaction mixture was heated to 55° C. The solvent was removed under reduced pressure. The crude was purified by reverse phase chromatography. First purification (start 95% [0.1% HCOOH]-5% [CH₃CN:CH₃OH 1:1] and finished 0% [0.1% HCOOH]-100% [CH₃CN:CH₃OH 1:1). Second purification (start 81% [25 mM NH₄HCO₃]-19%[100% CH₃CN] and finished 45% [25 mM NH₄HCO₃]-55% [100% CH₃CN]. The best fractions were pooled and the solvents removed to afford compounds:

2, LC-MS ES⁺ m/z=377.1; Rt. 2.01 min, method A. [α]_(D) ²³+7.6 (c 0.64, MeOH). mp 161.4° C. ¹H NMR (300 MHz, CD₃OD) δ ppm 0.91 (m, 3H), 1.26-1.43 (m, 10H), 1.57 (m, 1H), 1.67 (m, 1H), 3.60 (d, J=5.1 Hz, 2H), 3.82 (s, 3H), 4.13 (m, 4H), 4.24 (m, 1H), 7.41 (s, 1H). 3, LC-MS ES⁺ m/z=513.0; Rt. 2.49 min, method A. [α]_(D) ²³+32.1 (c 0.29, MeOH). ¹H NMR (300 MHz, CD₃OD) δ ppm 0.91 (m, 3H), 1.22-1.44 (m, 16H), 1.68 (m, 2H), 3.83 (s, 3H), 3.98-4.24 (m, 10H), 4.41 (m, 1H), 7.46 (s, 1H).

Preparation of 5

An aqueous solution of dimethylamine (6.67 mL, 132.8 mmol) and copper (I) iodide (19.28 mg, 0.13 mmol) were added to a solution of (R)-2-((2-chloro-5-methoxy-pyrimidin-4-yl)amino)hexan-1-ol (For synthesis see WO2012/136834) (500 mg, 1.92 mmol) in 1,4-dioxane (5 mL) in a steel reactor. The reaction mixture was heated to 160° C. overnight. The reaction was cooled and filtered through packed Celite and the solvent was evaporated to dryness to give a crude that was purified by column chromatography on silica gel to yield (R)-2-((2-(dimethylamino)-5-methoxypyrimidin-4-yl)amino)hexan-1-ol (250 mg, 0.93 mol). LC-MS ES⁺ m/z=269.1; Rt: 2.00 min, method A. ¹H NMR (300 MHz, CD₃OD) δ 0.90 (m, 3H), 1.25-1.47 (m, 4H), 1.58 (m, 1H), 1.67 (m, 1H), 3.05 (s, 6H), 3.61 (m, 2H), 3.77 (s, 3H), 4.21 (m, 1H), 7.35 (br s, 1H). [α]_(D) ²³−8.25 (c 0.64, CH₃OH). mp 86.1° C.

Preparation of 6

Compound 6 was prepared analogous to the procedure to prepare 5 with the exception that methylamine was used. LC-MS ES⁺ m/z=255.1; Rt: 1.85 min, method A. ¹H NMR (300 MHz, CD₃OD) δ ppm 0.91 (m, 3H), 1.26-1.44 (m, 4H), 1.56 (m, 1H), 1.66 (m, 1H), 2.81 (s, 3H), 3.60 (m, 2H), 3.76 (s, 3H), 4.18 (m, 1H), 7.32 (br s, 1H). [α]_(D) ²³+1.8 (c 0.59, CH₃OH). mp 86.1° C.

Preparation of 8

Step 1. Preparation of 7. TBDMSCI (7.53 g, 49.9 mmol) was added to a solution of 1 (10.0 g, 41.6 mmol) and Et₃N (11.6 mL, 83.2 mmol) in DMF (120 mL). The mixture was stirred at rt for 70 h. EtOAc and a 10% aq. NaHCO₃ was poured into the solution. The layers were separated and the organic layer was washed with brine (twice). The organic layer was dried over MgSO₄, the solids were removed by filtration, and the solvent of the filtrate was removed under reduced pressure to give an orange oil, purified by silica column chromatography using the following gradient: from CH₂Cl₂ 100% to 90%, CH₃OH 0 to 10% (with 5% aq. NH₃) to afford 7, as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 0.01 (s, 6H), 0.80-0.88 (m, 12H), 1.17-1.34 (m, 4H), 1.45 (m, 1H), 1.61 (m, 1H), 2.48-2.52 (m, 12H), 3.49 (dd, J=10.00, 6.50 Hz, 1H), 3.58 (dd, J=10.00, 4.70 Hz), 3.66 (s, 3H), 4.09 (m, 1H), 5.44 (s, 2H), 5.84 (d, J=9.09 Hz, 1H), 7.37 (s, 1H). LC-MS ES⁺ m/z=355.1, Rt: 3.76, Method: B). [α]_(D) ²⁰+53.33 (c 0.3, DMF). Step 2. Under N₂, bis(2-oxo-3-oxazolidinyl)phosphinic chloride (1.05 g, 4.11 mmol) was added portionwise to a solution of ((hydroxyphosphoryl)bis(oxy))bis(methylene) bis(2,2-dimethylpropanoate) (1.61 g, 4.93 mmol) and DIPEA (2.83 mL, 16.4 mmol) in anhydrous 2-methyltetrahydrofuran/DMF (20 mL/14.5 mL). The mixture was stirred at rt for 2 h. Step 3. Then 7 (729 mg, 2.06 mmol) in anhydrous 2-methyltetrahydrofuran (17 mL) was added and the mixture was stirred at rt for 2h. The reaction mixture was diluted with EtOAc and water, the organic layer was washed with brine (twice), dried over MgSO₄, the solids were removed by filtration, and the solvent of the filtrate was removed under reduced pressure, then purified by silica column chromatography using a mobile phase gradient: from heptane/EtOAc (80/20 to 0/100) to give 290 mg of 8 as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 0.84 (t, J=6.82 Hz, 3H), 1.12 (s, 18H), 1.18-1.34 (m, 4H), 1.41-1.65 (m, 2H), 3.42 (m, 2H), 3.74 (s, 3H), 4.03 (m, 1H), 4.61 (t, J=5.56 Hz, 1H), 5.60 (m, 4H), 6.44 (s, 1H), 7.45 (s, 1H), 8.77 (m, 1H). LC-MS ES⁺ m/z=547.6, Rt: 3.02, Method: B

Preparation of (2R)-2-((5-methoxy-2-((tetrahydrofuran-2-yl)amino)pyrimidin-4-yl)-amino)hexan-1-ol (9)

In a Schlenk flask, DOWEX(R) 50WX2 (100-200 mesh) resin (one spatula) was added at room temperature to a mixture of 1 (4 g, 11.3 mmol), 2,3-dihydrofuran (1031 μL, 13.5 mmol, 1.2 eq.) in anhydrous dichloroethane (99 mL). The mixture was stirred at 80° C. for 20 h. Additional 2,3-dihydrofuran (688 μL, 9.03 mmol, 0.8 eq.) was added and the mixture was stirred at 80° C. for 20 h. An extraction was performed with CH₂Cl₂ and water, and the layers were separated. The organic layer was dried over MgSO₄, filtered, and the solvent was removed under reduced pressure to afford the titled compound.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 0.84 (t, J=6.57 Hz, 3H), 1.18-1.33 (m, 4H), 1.46 (m, 1H), 1.58 (m, 1H), 1.74 (m, 2H), 1.96 (m, 2H), 3.41 (m, 2H), 3.61 (m, 1H), 3.64-3.73 (m, 4H), 4.04 (m, 1H), 4.65 (t, J=5.31 Hz, 1H), 5.73 (m, 1H), 6.00 (d, J=9.09 Hz, 1H), 6.54 (m, 1H), 7.42 (s, 1H). LC-MS ES⁺ m/z=311.3, Rt: 2.30, Method: B)

Preparation of (2R)-2-((5-methoxy-2-((tetrahydro-2H-pyran-2-yl)amino)pyrimidin-4-yl)-amino)hexan-1-ol (10)

Compound 10 was prepared according to the procedure to prepare 9, with the exception that 3,4-dihydro-2H-pyran was used.

¹H NMR (400 MHz, DMSO-de) δ ppm 0.85 (m, 3H), 1.17-1.66 (m, 12H), 1.82 (br d, J=4.55 Hz, 1H), 3.35-3.50 (m, 3H), 3.70 (s, 3H), 3.77 (m, 1H), 4.02 (m, 1H), 4.66 (m, 1H), 5.01 (m, 1H), 6.02 (d, J=8.59 Hz, 1H), 6.46 (t, J=10.11 Hz, 1H), 7.43 (m, 1H). LC-MS ES⁺ m/z=325.1, Rt: 2.45, Method: B)

Analytical Methods

      Method code         Instrument         Column         Mobile phase         Gradient $\frac{\begin{matrix} {Flow} \\ \left( {{mL}\text{/}\min} \right) \end{matrix}}{\mspace{11mu}\begin{matrix} {Col} \\ {T\left( {{^\circ}\mspace{14mu}{C.}} \right)} \end{matrix}\;}$     Run time (min) A Agilent 1100- DAD-MSD YMC-pack ODS-AQ A: 0.1% HCOOH in From 95% A to 5% A in 4.8 min, $\frac{2.6}{35}$ 6.0 G1956A C18 (50 × H₂O held for 1.0 min, 4.6 mm, B: CH₃CN to 95% A in 0.2 3 μm) min B Waters Acquity BEH C18 (1.7 μm, A: 95% 7 mM NH₄OAc/5% From 84.2 % A and 15.8% B $\frac{{0.3}43}{40}$ 6.07 2.1 × 100 CH₃CN (hold for 0.49 mm) B: CH₃CN min) to 10.5% A and 89.5% B in 2.18 min, hold for 1.94 min, and back to the initial conditions in 0.73 min, hold for 0.73 min

Supporting ADME Data.

Intrinsic clearance (CL_(int)). CL_(int) was determined in rat and human liver microsomes. Incubations were performed at 37° C., at a concentration of 1 μM of compound, and a microsomal protein concentration of 1 mg/mL. Serial samples were removed at intervals of up to 60 min and analyzed for the concentration of compound to determine its intrinsic clearance rate. Compound was incubated in rat and human hepatocytes (10⁶ cells/mL) at 1 μM for 0, 10, 20, 40, 60 and 120 min. Serial samples were removed at intervals of up to 120 min and analyzed for the concentration of compound to determine its intrinsic clearance rate.

Permeability and Efflux in vitro. The in vitro permeability and potential to be transported by P-glycoprotein (P-gp) was determined using an MDCK cell line transfected with human MDR1 (P-glycoprotein). Compound was added to the apical (A) or basolateral (B) side of a confluent monolayer of MDCK-MDR1 cells. Permeability in the A→B direction in absence and presence of GF120918 and in the B→A direction in absence of GF120918 was measured by monitoring the appearance of the test compound on the opposite side of the membrane using a specific LC-MS/MS method. The efflux ratio (B→A-GF120918/A→B-GF120918) was calculated to determine whether the test compound was a P-gp substrate.

Plasma stability. Plasma stability is measured in rat and human plasma for 7 or 24 h at 37° C. Compounds are incubated at 1 μM. Incubations are performed manually in a 24-well plate and serial samples (100 μL) are removed at various time points prior to quenching with acetonitrile.

Samples were analyzed by LC-MS/MS (without internal standard). Percentage remaining at each time point is calculated relative to the average peak area of the t=0 sample. Half-life (t½ in hours) is calculated from those data.

SGF stability and FASSIF stability. The stability of the prodrugs in simulated gastric fluid (SGF) in presence of pepsin and in fasted simulated intestinal fluid (FASSIF) supplemented with pancreatine and esterase was measured. Test compounds were incubated in vitro for up to 2 hours and samples were taken at different time points. Samples were analyzed for parent compound disappearance by LC-MS/MS. Percentage remaining at each time point is calculated relative to the average peak area of the t=0 sample. Half-life (t_(1/2) in hours) is calculated from those data.

Pharmacokinetics in rat. Prodrugs were administered orally to SD rats using aqueous solution at 5 mg/kg eq dose. Plasma samples were collected at different time points and the concentration of parent and prodrug was analyzed using LC-MS/MS. PK parameters were calculated using Phoenix WinNonlin 6.3. C_(max) (ng/mL) and AUC_((0-last)) (ng·h/mL) were determined for both prodrug and parent.

TABLE 1 Permeability in MDCK-MDR1 cell line. Papp A → B + Papp A → B − Efflux ratio Entry GF120918 GF120918 B → A/A → B 2 1.6 0.4 54 3 1.6 <0.2 >61 5 47 20 3.2 6 27.5 6.8 10 8 10 <1 >43 10 17 1.8 33

TABLE 2 Intrinsic clearance (CLint) in liver microsomes and hepatocytes. CL_(int) CL_(int) CL_(int) CL_(int) rat liver human liver hepatocytes hepatocytes Entry microsomes microsomes rat human 2  18   <7.7 20 <1.9 3  178* 297* 110 17 5 141 14 280 80 6  25 18 120 33 8 >347  n.d. >280 >280 9  27 115  n.d. n.d. 10 >347* 88-90 n.d. n.d. n.d. = not done, *an average of two data points

TABLE 3 Stability in simulated gastric fluid (SGF) and fasted simulated intestinal fluid (FASSIF) and stability in rat and human plasma. t_(1/2) SGF t_(1/2) FASSIF t_(1/2) rat t_(1/2) human Entry (h) (h) plasma (h) plasma (h) 2 >6 >6 >30 >30 3 >6 >6 >30 >30 5 >6 >6 >30 >30 6 >6 >6 >30 >30 8 3.9 0.1 <0.4 1 9 1 1.1 <0.4 <0.4 10 0.3 0.8 1.4 1.4

TABLE 4 Oral administration of 1 and prodrugs in rat. C_(max) AUC_((0-last)) C_(max) AUC_((0-last)) Entry prodrug prodrug Compound 1 Compound 1 1 n.a. n.a. 177 486 2 1360 2567 BQL BQL 5  88  144  37  60 6  129  206  47 114 n.a. = not applicable 

1. A compound of formula (I)

or a pharmaceutically acceptable salt, solvate or polymorph thereof, wherein R_(1A) is hydrogen or a substituted or unsubstituted C₁₋₃ alkyl; R_(1B) is selected from a substituted or unsubstituted C₁₋₃ alkyl, heterocycle, or a substituted or unsubstituted phosphoramidate; and R₂ is a C₁₋₈ alkyl optionally substituted by a hydroxyl group, —OSi(C₁₋₄ alkyl)₃, or an organophosphate group.
 2. A compound according to claim 1 wherein R_(1B) is a substituted or unsubstituted phosphoramidate and wherein R₂ is a C₁₋₆ alkyl substituted by a hydroxyl group.
 3. A compound according to claim 1 wherein R_(1A) or R_(1B) are methyl and wherein R₂ is a C₆-alkyl substituted by a hydroxyl group.
 4. (canceled)
 5. (canceled)
 6. (canceled)
 7. A compound according to claim 1, wherein R_(1A) and R_(1B) are methyl and wherein R₂ is a C₆-alkyl substituted by a hydroxyl group.
 8. A compound according to claim 1, wherein R₂ is a C₁₋₈ alkyl optionally substituted by a hydroxyl group, —OTBDMS, or —OP(═O)(OEt)₂.
 9. A compound according to claim 8, wherein R₂ is a C₁₋₈ alkyl optionally substituted by a hydroxyl group or R₂ is selected from the group consisting of:


10. A pharmaceutical composition comprising a compound according to claim 1, or a pharmaceutically acceptable salt, solvate or polymorph thereof, together with one or more pharmaceutically acceptable excipients, diluents or carriers.
 11. A method for treating a viral infection, comprising administering to a subject in need thereof the compound according to claim 1 in an effective amount to treat the viral infection.
 12. The method of claim 11, wherein the viral infection is a hepatitis B infection.
 13. A method for treating an immune disorder, comprising administering to a subject in need thereof the compound according to claim 1 in an effective amount to treat the immune disorder.
 14. A method for treating cancer, comprising administering to a subject in need thereof the compound according to claim 1 in an effective amount to treat the cancer.
 15. A compound selected from the group consisting of:

or a pharmaceutically acceptable salt thereof.
 16. A pharmaceutical composition comprising the compound according to claim 15, or a pharmaceutically acceptable salt thereof, together with one or more pharmaceutically acceptable excipients, diluents or carriers.
 17. A method for treating a viral infection, comprising administering to a subject in need thereof the compound according to claim 15 in an effective amount to treat the viral infection.
 18. The method of claim 17, wherein the viral infection is a hepatitis B infection.
 19. A method for treating an immune disorder, comprising administering to a subject in need thereof the compound according to claim 15 in an effective amount to treat the immune disorder.
 20. A method for treating cancer, comprising administering to a subject in need thereof the compound according to claim 15 in an effective amount to treat the cancer. 